1. Field of the Invention
The invention relates to a female coupling element including a locking member for locking a male element, the female coupling element extending along the coupling axis of the coupling. The invention also provides a coupling for joining together two fluid pipes, the coupling comprising both such a female element and a male element.
2. Brief Description of the Related Art
In certain fluid connection applications, in particular for hydraulic brake circuits of a motor vehicle, the coupling needs to present small radial size and the dimensions of the fluid ducts are relatively small. In order to ensure that the coupling is radially compact and in order to allow the male and female elements thereof to turn relative to each other, the members for locking the male element in the female element of a prior art coupling are generally constituted by balls housed in the female element. In the locked position, the balls are held between a housing in the female element and a corresponding cavity in the male element, such as an annular groove. The balls make point contact with those parts, such that when operating pressures are high, they transmit large loads via small areas. These loads lead to surface bruising in the ball-receiving cavity of the male element, and in the housing of the female element, thereby degrading the quality of the locking of the coupling.
U.S. 2,344,740 describes a locking member constituted by a cylindrical locking portion, a connecting portion, and a control portion. The connecting portion presents a width that is slightly greater than the width of the other portions. The locking member is subjected to combined movement in pivoting and in translation, thereby conserving relatively good radial compactness for the coupling.
Nevertheless contact between the male element and the locking portion takes place only along a linear segment, thereby giving rise, as with balls, to bruising of the contacting surfaces, and also to a relatively loose locking.
In addition, in order to allow the locking member to move, clearance is provided between the cylindrical locking portion and the housing that receives it in the coupling body. The connecting and control portions can move laterally around the axis of the coupling, thereby running the risk of putting the locking member off-axis. Such a sloping position can lead to jamming or even to breakage of the locking member during locking and unlocking movements of the coupling.
Similarly, EP-A-0 722 063 describes a coupling in which the contact area between the male element and the locking portion of the locking member is relatively small, thereby also leading to bruising of the contacting surfaces and limiting the strength of the locking.